Hair growth on a scalp of a human occurs as a hair shaft emerges from a hair follicle. More specifically, hair growth may be characterized by three phases of a hair growth cycle. The hair shaft actively grows, i.e., lengthens and thickens, during the anagen phase of the hair growth cycle. The hair shaft stops growing during the transitional catogen phase, and rests during the telogen phase of the hair growth cycle. The hair shaft is shed from the scalp at the end of the telogen phase and replaced by a new hair shaft from the same hair follicle, and the hair growth cycle starts again. Any disruption in the aforementioned hair growth cycle caused by, for example, aging, stress, drugs, disease, hormonal fluctuations, and/or nutritional changes, may lead to hair loss.